Field of the Invention
The present invention relates to an illumination apparatus used for plant cultivation. The present invention also relates to a method of cultivating a plant.
Description of the Related Art
It is considered that there is a case where a polarization state of light gives a certain influence on growth or the like of a plant (Patent Literatures 1 and 2). For example, in Patent Literature 1, an apparatus for controlling organism behavior including a polarized light irradiation mechanism is disclosed and it is shown that the growth of Arabidopsis was accelerated by irradiating the same with exclusively red right-circularly polarized light in an experiment using the apparatus.
On the other hand, studies have been performed conventionally on the influence that is given to a plant by a wavelength of light with which the plant is irradiated (for example, Patent Literatures 3 and 4, Non-Patent Literature 1). In Non-Patent Literature 1, there is a description suggesting that blending of red light and blue light in a balanced manner is necessary for a healthy growth of a plant and a ratio of red light/blue light of 10/1 or 5/1 is suitable in the unit of a photon flux density.